Stair climbing wheel chair



Aug. 3, 1965 T. R. PORTER 3,198,534

STAIR CLIMBING WHEEL CHAIR Filed Oct. 18, 1963 5 Sheets-Sheet 1 Aug- 3,1965 r. R. PORTER 3,198,534

STAIR CLIMBING WHEEL CHAIR Aug. 3, 1965 T. R. PORTER 3,198,534

STAIR CLIMBING WHEEL CHAIR Filed Oct. 18, 1965 5 Sheets-Sheet 5 UnitedStates Patent() sns/asse STAIR CLE/ING WVHEEL CHIR Than Robinson Porter,329 E. l3th St., Apt. A, New York, NSY. Filed Get. 16, 1963, Ser. No.326,233.3 1S Claims. (Cl. Mtl-5.22)

This invention pertains to an improved type of invalid ychair whichenables the occupant under his own power to propel himself overobstacles such as curbs and stairs and which chair can still 'beoperated by lthe occupant on a flat, level surface yas -an ordinary handoperated, folding wheel chair without undue sacrifice of qualities suchas collapsibility, maneuverab-ility without damage to oo-rs or stairs,compactness, lightness, and economy.

Although there have been many proposals in the past for stair climbinginvalid chairs, they have been mostly very heavy, expensive,non-collapsible devices which are too large to negotiate narrow stepsand doorways. Furthermore, previous attempts at obstacle-climbinginvalid chairs which employ endless tr-ack devices either provide nomeans at .all for supporting the straight, ground engaging part of thetracks or provide for a very complicated Iand expensive battery of smallwheels.

The object of this invention, therefore, is to overcome these defects byproviding an invalid chair which:

(l) :can be propelled by .the occupant on a level, fiat surface withoutmarring floors, r-ugs, or other surfaces;

(2) is capable by means of endless track type tires of negotiatingstreet curbings Iand `any stairs with 'average height risers and depthlof tread as found in oce buildings and homes, including spiralstaircases, even .in the presence of at least 'as much litter andmoisture `as would not unduly hinder a person walking up the stairs,without damaging the stairs, without necessitating undue time inshifting from the stair climbing function to ordinary operation and vicevers-a, and without the installation of any ramps, electrical outlets.or any other devices not integr-al parts 4of the chai-r;

(3) has a simple means of supporting the above-mentioned endless tracksevenly all along the straight, ground engaging part of said tracks;

(4) is so compact that it can be turned on a stair landing that is nolarger than three by three feet, can be folded and stored in a standardautomobile or taxicab, is no wider than its own seat when in operation,and can even be made narrower for negotiating tight places;

(5) can accomplish the foregoing without the necessity of unreasonableforce applied by the occupant and without the sacrifice of comfort,safety, or extra devices such as adjustable foot rests, means forallowing the occupant to get on and off from the side, and the like. y

The following is a brief gener-al description of the means by which thisinvention accomplishes the foregoing objects.

On each side of the chair are two endless belt type tracks, one towardthe front and one toward the back of the chair and articulated by meansof two coaxial, laterally spaced cog wheels and which have exible rubbertires which roll on and are supported by metal rims each of which has astraight lower. section and approximately semicircular end sections andwhich are adjustable by means of hydraulic jacking devices and/ orsprings so that either the straight parts of the said tires form aground engaging track for mounting obstacles or the semicircular endsections are in contact with the floor with the floor tangent to thetires near the rear of the chair thus enabling the tires to functionlike ordinary circular tires supporting the rear of the chair. A singlecaster type wheel supports the front of the chair.

FIG. l is a side elevational view showing the chair in the normaloperating position for rolling on a flat, level surface.

FIG. 2, viewed from above, is an enlarged detail of the means forsupporting the front caster type wheel.

FIG. 2A, viewed from above, is an enlarged detail of the front wheelsupport showing the method by which the -front wheel is to be foldedwhen the chair is collapsed.

FIG. 3 shows the chair in successive stages of starting up the sta-irs.

FIG. 4 shows two side elevational views of the chair. The main position,shown entirely by solid lines, shows the chair entirely on the stairs.The `alternate position with a few parts shown by phantom lines, showsthe chair at the top of the stairs as it is about to be converted backto an ordinary wheel chair.

FIG. 5 is a side view detail of the rim and tire and a cog wheel todrive it.

FIG. 6 shows an alternative method of making the tire roll on a fixedrim.

FIG. 7 shows a pendulum type automatic leveling device.

FIG. 8 shows a detailed cross section of a tire and rim with a cog wheelto drive it and a set screw type brake.

FIG. 9 is a front elevation of the left handfside of the chair showingthe lateral placement of the tires, hand rim, and various other parts inplanes A through E, which planes are perpendicular to the plane of thedrawing. The footrests, for simplicity, are not shown in this gure.

FIG. l0 shows a cross section of FIG. 6.

FIG. l1 shows a side elevation of the chair in the position to beginmounting stairs.

FIG. l2 shows a detail of the stair climbing drive mechanism.

FIG. 13 shows a detail of the lower right corner of FIGS.

FIG. 14 shows a cross section of the upper part of FIG. 12.

FIG. l5 shows a detail of the Very small gear shown in FIG. l2.

The operation and construction of this'invention will become more clearfrom the following detailed description.

As this invention is laterally symmetrical, with the exception of part32 to be described later, only one side is shown and described.

The chair unit, except for the wheels and accompanying hydraulicadjustment mechanisms may be a conventional wheel chair with a tubularframe, hand grips for propulsion by an attendant, a back and seat offlexible material such as cloth or leather, and footrests. As there isno mechanism above the seat and in front of the back, a skirt shieldsuch as is on most 'conventional wheel chairs is not really necessary,although the chair of this invention could be equipped with one.V

This chair is folded in the conventional manner by raising the seatframe Il thus folding the X braces 13 together so that they arevertical. The chair of this invention has a curved frame member 26instead of the usual rectangular frame member so as not to interferewith the stairs, as is evident from FIG. 4. The X braces are situatedslightly forward of their position on a conventional wheel chair so asnot to interfere with the frame member 26. The frame member 2l) is anarc of a circle with center at 9.

The front of this chair is supported by a small caster type wheel 48(FIGS. 1, 2 and 4) which is supported by two rods 37a and 37b (FIGS. land 2) which are pivotally connected by pins 36a and 35h underneathframe member 33, said rods being pivotally connected to each other byrod 38 which is connected to the wheel. The non-pivoted ends of rods 37aand 37b are not fastened to frame member 33 but are underneath and slidealong frame member 33 when the chair is folded. The caster is very smallsince the stair climbing feature makes it unnecessary to provide a largewheel for great facility in rolling over small obstacles.

The rear of the chair of this invention is supported by the tires 17 and51 (FG. 1) which are mounted on rims d3 and 45, which arecross-sectionally outwardly concave as is shown by FIG. 8. The tires 17and 51 are made of exible rubber with notched tread 46 (FIG. 1). Thetires have attached to them by small pins two rows of small ballbearings 63 (FIGS. 5 and 8) which enable the tires to roll around on therims while the rims remain xed with relation to the chair. There is alsoeither a thin band of very tiexible spring steel or several fine wireson the inside of each tire with metal pockets 62 which t the teeth ofthe cog wheels 155, 1*; and 44 (FIG. l) which engage the tires throughslots in the rims i3 and 4S. This exible band of spring steel or thewires prevent the tire from stretching and the metal pockets prevent theteeth from damaging the rubber.

. The rims 43 and 45 are adjustably supported at three places, thefront, middle, and rear as canbe seen in FIG. 1. The front of rim 43 ispivotally attached by means of pin 39 to a bar 27 which articulates withand slides upon or in another bar 14 by some means such as a set of twopins on bar 27 that tit into a slot in bar 14 or by bar 14 being tubularwith bar Z7 fitting inside it like a telescope or by any other simplemeans. For the middle support, a light flange 50a for mounting wheels44, is attached to rim 43 thus bearing axle 49 to which the two cogwheels 44a and 4411 are fixed and are laterally spaced so that one cogwheel engages tire 17 and the other, tire 51 with tire 51, as is shownby FIG. 9, being on the outside. Looking back to FlG. 1, the axle 49 issupported by a tubes-1 which iits very accurately into the tubular framemember 16. Rim 45 is similarly attached to bar 41. For the rear support,rim 45 is pivotally attached at pin 34 to another tube 22, which titsinto tube 15, which in turn ts into tube S which is mounted by means ofa hollow pin 2 to a hydraulic pump 1, which has a plunger 3, which isoperated by a lever 4 pivoting at 5, lever 4 being also an armrest.Armi-est 4 is made with a shoulder 6 that prevents it from going downany fartherV than its horizontal position. Furthermore, it has a slightcurve near the pivot point so that it can be raised to a verticalposition without interfering with frame member-10.

A cog wheel 19 is a ring gear supported by the small cog wheel 26 andthe small dummy cog wheels 26a and 26h, the axles of which are mountediny ange Stic (FIG. 12).

The wheel 19, having a diameter of about five or six inches, has largeteeth on the outer side of its periphery and very small, ne teeth on theinside of its periphery, said small teeth engaging with small teeth oncog wheel 26 which has a diameter of only about one half inch. Thewheels 26a and 2eb are dummy wheels for supporting wheel 19. T he axlesof all the wheels 26 are supported by frange 56C. Coaxial with wheelitiis a hand rim 21 connected to wheel 26 by means of a light sheet metalange 7h (FG. 9) or by spokes or other convenient means. A small handlelike the wheel spinner on an automobile steering wheel is attached tothe hand rim, said spinner being capable of being folded upV or pulledout to be used as a crank handle to turn the hand rim continuously inone direction if desired byv the occupant.

To prevent wheels 13 and l@ and adjacent mechanism from falling awayfrom the chair, a pin on the inside of ange Stic at about the center ofwheel 19 its into a slot in small, light, liat bars 24a and Zlb whichare welded to the frame at 29 and other points at the ends of bars 24aand 24h.

Wheel 18, having a diameter of about two inches, is mounted to rim 43and engages tire 17 in a manner similar to that of wheel 19. Attachedcoaxially with wheel 18 is a knob 18a (FIGS. 1 and 9) which is shapedlike a doorknob having approximately the same diameter as cog wheel 13.

The occupant propels the chair by turning tire 17 by either of twoalternative methods thus turning cog wheel 44a which turnsV cog wheel44h, which is rigidly mounted on the same axle as 44a, thus turning tire51. The two alternative methods of turning tire 17 are by turning knob18a, which turns cog wheel 18 which engages with tire 17, or by turninghand rim 21, which turns wheel 26, which turns wheel 19, which engageswith and turns tire 17.

The tire 17 is raised to the position of FIG. 1 for normal operation orlowered to the position of FIG. 11 for mounting obstacles simply bybeing pushed down or pulled up by the occupant. A small catch 25 (FIG.l), consisting either of a set screw in part 14 that screws down againstpart 27 or a pin on a spring which pin slips into notches on part 27 orsome other simple type of easily releasable catch, holds tire 17in-either the position of FIG. l or FIG. 11 or any other positiondesired. For mounting small obstacles in a forward direction, tire 17 isput into a position slightly higher than the position of FIG. 1l but nothigher than the footrests 47.

The chair mounts stairs backwards beginning with the position of FIG.11. As the tire 51 turns, the notches 46 engage the edge of the step andthe back of the chair begins to rise.

As the rear of the chair rises, the seat will tend to be tilted forward.Valves 2 and 7 are opened to allow fluid to How out of tube 16, throughframe members 12 and Y10, and out'of tube 8 to allow rods 22 and 41 toretract. Either the occupant operates these valves or there is a smallpendulum 69 (FIG. 7) which opens and closes the valves to keep the chairlevel automatically. As the pendulum 69 swings to the right, the opening67 is uncovered while the opening 66 remains covered; and similarly whenpendulum 69 swings to the left, opening 65 is uncovered. There is a setknob at the pivot point 63 `for iixing the valve in any position at thewill of the occupant. Also, the pendulum can be bent at point 63 so asto make it hang vertically with the chair .tilted if desired. For thevalve in the hollow pin 2, the bar covering openings 66 and 67 is in theform of a cylinder inside the hollow pin, but the principle is the same.To prevent any tilting forward at all, the chair can be tilted slightlyback at the beginning by adjusting the bar of the pendulum.

FGS. 1 and l2 show springs 15a and 16a, which hold up most of the weighton the middle and 'rear supports thus greatly reducing the necessarypressure in the hydraulic fluid.

As the chair mounts the stairs, the tires 17 and 51 gradually come to amore nearly straight line as is shown by FIG. 3 until the chair isentirely on the stairs as is shown by FIG. 4 with the tires in Contactwith several steps like 57, 58 and 59. There is no reason that the angieof elevation of the liat parts of tires 17 and 51 need be the same forthe two sides of the chair. Hence this chair can negotiate triangularsteps and spiral staircases and other irregular obstacles.

When the chair nearly reaches the top of the stairs and tire 51 is up inthe air entirely oif the stairs, it falls down on the stair landing asin the atlernate position of FIG. 4, the valve 2 (FIG. 1) having beenturned some time previously to the position allowing uid to flow into,but not out of, tube 8. Tire 51 continues to fall down until the plane53 through the center of gravity of the chair is to the right of 59 andthe back of the chair is supported by tire S1. As the front of the chaircontinues to go up, the chair leans back. The occupant can either let itlean back, or he can jack himself up with the hydraulic jack. When point30 is above and to the right of point 59 in FIG. 4, tire 17 will tend torotate clockwise about point 39 while tire 51 will tend to rotatecounterclockwise, both of which rotations will cause the wheel 44 tocome down to the floor.

It the chair has not been jacked to an upright position by means of tire51, a little more jacking of tube 41 is necessary to right the chair. Ifthe hydraulic fluid is compressible or if there is a compression springin reservoir 1, the occupant can pump the jacks at his convenience.

When the chair is at the top of the stairs in an upright position, theoccupant simply pulls the tire S1 up to the position of FIG. 1. If nomore stairs are to be mounted, the ltire 17 is also pulled up. If thechair has reached a landing and more stairs are to be mounted, the tire-17 can be left down. The chair must skid a little to turn with the tire17 down because the t-ire 17 is in contact with the lloor along astraight line in the down position, and a straight line cannot possiblyit on a circle. Hence if the landing has an expensive rug or easilyscratched surface, .the tire 17 must be raised anyw-ay so as not todamage the floor by skidding. It can be raised just slightly to theintermediate position, as herein before described, as a safety factor sothat in case caster wheel 48 should accidentally slip olf the landing,the chair would still be caught by the tire v1'7.

For descending stairs, the procedure for ascending is simply reversed.

The common center of the arcs of 14, 24h and 27 (FIG. 1) is axle 49. Thecenter of the arcs of lo, 24a, and 41 is the pin 3@ when in the positionof PEG. 11. Either axle d pivots about point Sil in the position of FIG.1 or point Si@ pivots about point di), but not both. Thus in theposition of FiG. 1, bar41 cannot retract even if the hydraulic fluidleaks out because point 39 is not at the center of the arc of bar 41.Therefore for normal operation the chair is not supported by thehydraulic fluid.

When 41 is fully retracted into 15 (FIG. 4), the axle 49 is above theend of tube 16. To accommodate this axle, -there is a slot 28 which, ascan be seen in FIG. 1, does not extend far enough to `.allow any lluidto escape. As frame member 2@ is Welded to tube 16, there isconsiderably rigidityrso that slot 23 does not unduly weaken the frame.

The center of the arc of the part of tire 17 between wheel 19 and wheelte is point 42 as shown by FIG. l. The center of the arc of the part oftire 17 between wheel 19 and the front of tire 17 is point 52 as shownby FIG. l. it is important for tire 17 to have approximately the sizeand shape shown in order for it .to fit well on the steps, giving goodbalance, and still allow for accessibility of hand rim 21 and knob 13aand still allow the hat bars 24 to be of such a length and position thatthey will not project out beyond the frame members of the chair and snagor gouge things.

Since, with the front wheel turned back, there is no part of this chair,exclusive of footrests, which projects forward beyond the front framemember of the chair, this chair can be driven up against a bureau orsink or the like. Also, with the arm rests in the vertical position, itcan be driven under a table or desk.

Referring to FIG. 1 and the lettered planes A through E perpendicular tothe plane of the paper of FIG. 9, in plane A are tube 16, bar 41, andframe member 20. Parts 1d and 27 and bars 24.1 are in plane B. As parts14 and 27 may be made at, there is room in plane B for 1d and 24a tocross each other las is shown in FGS. l and 9. in plane C are tire 17and tubes 8 and 15 with `bar Z2. Because the rims do not rotate as on anordinary wheel chair, there neednt be much clearance between pianes Band C thus allowing for maximum compactness. ln plane D are the hand rimZ1, knob 13a, frame member 1e (except where it curves over to meet framemember 2d), seat frame member 11, frame member 12, and rear .tire 51.The footrest support 35 is 'also in plane D although the bottomhorizontal part of the footrest support 31 is bent in to plane Ato meetframe member 33.

If greater longitudinal Ycompactness is desired, hand rim 21 may be inplane E so that tire 51 and hand rim 21 will not be in the same plane,thus 'allowing tire 51 to be drawn up higher toward frame member 20. Inthe position of FG. 11, the tire 51 can be drawn up all the way anywaysince the hand rim 21 is far enough forward not to interfere. If minimumwidth is not desired, knob 13a and hand rim 21 may be in plane E merelyto make them slightly more accessible to the occupant. But if minimumwidth is desired, nothing need be in plane E so that the entire chair isno wider than the seat.

The point 5d `at which the tires touch the oor in normal operation isdirectly under rear frame member 10 as is the case for a conventionalrear drive Wheel chair, thus giving stability with compactness.

To prevent the chair from plunging down the stairs if the hand rim isreleased, there is a ratchet having means for being released at the willof the occupant for descending stairs, which releasing means must beconsciously held to be released, with a spring to return it to itsengaged position so that the occupant must hold it in its releasedposition all the way down the stairs. If the occupant becomesincapacitated for some reason such as fainting, the ratchet willautomatically engage and stop the chair. The ratchet operates on any ofthe wheels 1S, 19 or 44 but might most conveniently be installed on theaxle of hand rim 21 with a small cable coming out of the axle of handrim 21 with a ring on the end of the cable, which ring when pulled withone finger releases the ratchet thus allowing the rest of the hand to beused to hold the hand rim. For normal operation, when the ratchet is notbeing used,'the cable may be hooked onto the wheel spinner on the handrim or any other convenient place. v

For a brake, screw 6@ is screwed into a small bracket 61 which isrwelded to rim 43 at any convenient place.

When screw 6o is `screwed down against tire 17, the tire is clamped tothe rim and cant r-oll, thus preventing the chair from moving.

As an alternative method of enabling the tires to roll around the rims,V64a and 64b are flat plates in FIG. 6 joining a series of cylindricalrollers 65a, b, 65C thus forming a chain similar to a bicycle chain,which is imbedded in the rubber of the tire. As on a bicycle chain,

45 the spaces between'the rollers receive the teeth of the cog Wheels1S, 19 and de. The plates 64 areslightly narrower than the diameter ofthe cylindrical rollers 65 so that only Kthe rollers 65 are in contactwith the rim 43 thus allowing the tire to roll freely around the rim.The tire in this case need not even be continuous but can be in the formof little blocks of rubber spaced a small distance apart so as to allowfor greater ilexibility.

The following may be Iattached to this chair as optional access-Orres.

A small crank 32 (FIG. 9) connected by a flexible means such as a chainor cable 71 to the opposite side of the chair can be turned to shortenthe length of the chain thus partially folding the chair to make ittemporarily narrower for going through tight places.

There may be a small crank handle imbedded in knob 18a so that it can behinged in flush with the knob to be out of the way or can be hinged outto be used to turn knob 18a continuously in one direction instead ofturning a little and then get-ting another grip to turn again.

For operation by a person having only one hand, there can be a exibledrive shaft connecting the axle of wheel 18 or 26 to its mate on theother side Vof the chair, said flexible drive shaft being passed throughthe chair between the two X braces.

For rapid opera-tion, on a city street for instance, there can be asmall cog wheel that replaces knob 18a and which is connected by a chaindrive to a large crank which is up near the arm rests. This crank wouldbe similar to the pedals and, sprocket on a bicycle.

The foot rests can be made adjustable just as they are on manyconventional wheel chairs so that for more compactness resulting insmaller turning radius, they can be pulled in under the seat of thechair on each side of wheel 48 or turned out or any other Way thatadjustable footrests normally turn.

Axle 49 may be made in two parts 49a and 4% as shown by FIG. 13, with49h having a keyed shaft connected to cog wheel 44!) and fitted into ahole in the other shaft 49a connected to cog wheel 44a so that forsustained operation as an ordinary Wheel chair without the stairclimbing feature, tire 51 may be disengaged by simply pulling the axleout. A small catch holds the two parts of the axle together.

The tire 51 can be either hooked up somewhere on the chair, on flange56a for instance, or, by means of a wing nut on the pin 2, tire 51 andits accompanying hydraulic adjusting mechanism can be removedaltogether.

For -added rigidity there can be spokes for the rims 43 and 45. For theiiat parts of these rims, there can be a wire spoke 40 (FIGS. 1 and l2)stretched over` a small spacing block 39.

As an additional safety device, there can be a small rod 38a which canbe either folded up out of the way as is shown by FIG. 1 or let downagainst the step as in FIG. 4 to prevent the chair from skidding downthe stairs if there is insuiiicient traction.

Having set forth a description of this invention, I claim:

1. An improved type of stair climbing wheel chair comprising a pair ofmetal supported, closed curve tracks on each side of said chair, thetracks in each pair having a straight ground engaging section and eachpair of tracks being adjustablevvertically at three places to vary theangle between said straight sections, closed curve rims which are crosssectionally approximately semicircular and concave outward, one of saidrims being positioned with its front end approximately at the front ofthe chair and its rear end at the rear of the chair, the other one ofsaid rims having its front end slightly forward of the rear of thechair, thus longitudinally lapping and being laterally spaced slightlyfrom the that described rim, with the rear end of the second describedrim projecting rearwardly from the back of the chair, said iirstdescribed rim having an arcuate upper section, a longitudinallystraight, ground engaging lower section, and substantially semicircularend sections, the second described rim having longitudinally straightupper and lower sections and substantially semicircular end sect-ions,said front semicircular end section of the second described rim havingthe same center and radius as the rear semicircular end section of therst described rim.

2. An invalid chair as in claim 1 having, on each side, two flexible,closed curve, tread bearing tracks continuously supported by the rimswith means for said tracks to roll freely around said rims while saidrims remain fixed with relation to the chair, said tracks having metallined notches for receiving and engaging with cog wheel teeth on theinner side and having means imbedded in said tracks for preventingstretching of said tracks.

3. An invalid chair as in claim 2 with means of articulating both saidtwo rims and the two tracks, said articulating means consisting of avpair of coaxial, laterally spaced wheels having a supporting axlepositioned at the common center of the front semicircular section of therear rim and the rear lsemicircular section of the front rim, saidlaterally spaced wheels having teeth such that the teeth of the innerone of said wheels engage the front track through a slotin the front rimand the teeth of the outer one of said wheels engage the rear trackthrough a slot in the rear rim, the axleV being supported on the Vrimsby a ange on each side of said rims.

4. An invalid chair as in claim 3 with, on each side, -a hydraulicallyextendable' and retractable support which consists of a rod that iitsinto a tube like a telescope, both of which rod and tube are in theshape of an arc of a o circle which hydraulic support verticallypositions said axle the center of the arc of said hydraulic supportbeing near the floor and approximately under the front frame member ofthe chair.

5. An invalid chair as in claim 4 having, on each side, a hydraulicallyextendable support for the rear end of the aforementioned rear rim, saidhydraulically extendable and retractable support being pivotable both atits point of connection with the aforementioned rear rims with saidhydraulic support being attached to the chair behind the back of saidchair.

6. An invalid chair as in claim 5 having, inside of the hydraulicsupports, a coil spring for holding up most of the weight on thehydraulic supports.

7. An invalid chair as in claim 6 having, on each side, a hydraulic pumpwithk a handle for pumping hydraulic fluid into the hydraulicmechanisms, said handle serving as an arm rest attached pivotally to theframe of the chair of this invention in such a way that it may berotated to a vertical position to permit free side access to the chair.

S. An invalid chair as in claim 7 having, on each side, an extendableand retractable support in the shape of an arc of a circle for the frontend of the front rim the center'of the arc of said support being thewheel supporting axle when said hydraulic support is fully extended fornormal operation, the support of this claim being pivotally attached tosaid front rim at the center of the arc of the hydraulic support, thelength o'f this extendable and retractable support being xable wheredesired by the occupant by means of a small adjustable catch.

9. An invalid chair as in claim 8 having, on each side, a driving meansconsisting of a small knob or crank or both connected coaxially with acog wheel of approximately the same diameter as said knob or crank, theteeth of said cog wheel engaging with the front track through a slot inthe front rim.

10. An invalid chair as in claim 9 having, on each side, a driving meansconsisting of -a hand rim or crank or both about tive or six inches indiameter coaxially connected with Va small cog wheel about a half inchin diameter, which small cog wheel has small teeth that engage withteeth on the inside of the periphery of another wheel of much largerdiameter, said larger wheel having teeth which engage with and drive thefront tracks.

11. An invalid chair as ink claim 10 having a flexible drive shaftconnecting the axle of said driving means with its mate on the otherside of the chair to provide for operation by one-armed occupant.

12. An invalid chair as in claim 11 having on each side, a means forremoving the rear rim along with its accompanying track and thehydraulic support, said means consisting of a means of removing the pinon which the support is connected to the frame of the chair togetherwith `a keyed axle for the one of the wheels which engages theaforementioned rear track, which axle fits into a similarly shaped keyedhole in the axle of the one of the Wheels that engages the front trackwith a snap ball catch holding the above-mentioned axles together sothat they operate as one axle while allowing them to be pulled apartlaterally.

13. An invalid chair as in claim 12, having, on each side, a means ofhooking the rear rims and accompanying tracks in an inoperable positionwith the two sections of the axle disengaged from each other.

14. An invalid chair as in claim 13 having a single small caster typewheel positioned laterally in the middle of said chair and under thefront of said chair, said Wheel being supported by two rods in ahorizontal plane just underneath the lowest side frame members of saidchair, said rodsrbeing centrally pivoted forming an X and pivotallyconnected at the front end to the side frame members of the chair, theother ends of said rods being positioned underneath, but not connectedto, the side frame members of the chair so that said nonconnected endscan slide from front to back of the chair as the said rods pivot on eachother so yas to allow the side frame members to come closer together tofold up the chair.

15. An invalid chair as in claim 14 having a means for temporarilynarrowing said chair by partially folding it up with the occupant seatedin said chair, said folding being accomplished by the occupant himselfby means of a small crank mounted on the side frame member of the chairon one side only, said crank being connected to and capable ofshortening a chain or other exible tie means connecting the side framemembers, said shortening causing the Width of the chair to be decreasedwith a corresponding raising `of the seat.

16. An invalid chair as in claim 15 having, on each side, a ratchetsafety device which unless consciously held disengaged will engage :andprevent the chair from rolling down the stairs, said ratchet devicebeing connected to the axle of one of the Wheels, said ratchet beingprovided with a means for hooking it in the disengaged position when thestair climbing mechanism is not being used.

f 17. An invalid chair as in claim 16 having, on each side, a brakeconsisting of a small U clamp at any convenient place on said rim with aset screw screwed into said U clamp which set screw clamps a track toits supporting rim thus preventing said track from rolling.

18, An invalid chair as in claim 17 having, for the valve of yeachhydraulically extendable and retractable support, a pendulum levelingdevice for changing the valves to the three positions inflow, outow, andstop.

References Cited by the Examiner UNITED STATES PATENTS 6/56 McLaughlinISU-9.24 3/64 Greub 280-'5.2Z

1. AN IMPROVED TYPE OF STAIR CLIMBING WHEEL CHAIR COMPRISING A PAIR OFMETAL SUPPORTED, CLOSED CURVE TRACKS ON EACH SIDE OF SAID CHAIR, THETRACKS IN EACH PAIR HAVING A STRAIGHT GROUND ENGAGING SECTION AND EACHPAIR OF TRACKS BEING ADJUSTABLE VERTIFICALLY AT THREE PLACES TO VERY THEANGLE BETWEEN SAID STRAIGHT SECTIONS, CLOSED CURVE RIMS WHICH ARE CROSSSECTIONALLY APPROXIMATELY SEMICIRCULAR AND CONCAVE OUTWARD, ONE OF SAIDRIMS BEING POSITIONED WITH ITS FRONT END APPROXIMATELY AT THE FRONT OFTHE CHAIR AND ITS REAR END AT THE REAR OF THE CHAIR, THE OTHER ONE OFSAID RIM HAVING ITS FRONT END SLIGHTLY FORWARD OF THE REAR OF THE CHAIR,THUS LONGITUDINALLY LAPPING AND BEING LATERALLY SPACED SLIGHTLY FROM THEFIRST DESCRIBED RIM, WITH THE REAR END OF THE SECOND DESCRIBED RIMPROJECTING REARWARDLY FROM THE BACK OF THE CHAIR, SAID FIRST DESCRIBEDRIM HAVING AN ARCUATE UPPER SECTION, A LONGITUDINALLY STRAIGHT, GROUNDENGAGING LOWER SECTION, AND SUBSTANTIALLY SEMICIRCULAR END SECTIONS, THESECOND DESCRIBED RIM HAVING LONGITUDINALLY STRAIGHT UPPER AND LOWERSECTIONS AND SUBSTANTIALLY SEMICIRCULAR END SECTIONS, SAID FRONTSEMICIRCULAR END SECTION OF SECOND DESCRIBED RIM HAVING THE SAME CENTERAND RADIUS AS THE REAR SEMICIRCULAR END SECTION OF THE FIRST DESCRIBEDRIM.